An optical module that includes a semiconductor optical device usually provides an optical receptacle for optically coupling the semiconductor optical device with an external optical fiber. A Japanese patent application laid open No. JP-H08-334654A has disclosed such an optical module. When an optical receptacle implements a coupling fiber to optically couple the semiconductor optical device with an external fiber to be set within the optical receptacle and the coupling fiber shows stress-sensitive optical characteristics, the optical performance of the optical receptacle, in particular, a polarization maintain function thereof, is often degraded by a stress induced during a process to assemble the optical receptacle with a device that installs the semiconductor optical device or an optical processing device whose performance depends of the polarization of an optical signal incoming through the optical receptacle.